The present invention concerns the use of alkylmonoglucosides and more particularly n-butyl-xcex1-D-monoglucopyranose, named hereafter xcex1-butylglucoside as molecular vector, and the preparation of new compounds obtained by grafting xcex1-butylglucoside onto certain compounds and their uses.
We have noted that a need existed to modify numerous cosmetic or pharmaceutical active ingredients and/or food ingredients in order to improve:
their bioavailability
their toxicity
their liposolubility
their hydrosolubility
The present invention proposes to respond to these needs. It concerns the use, in pharmaceutical, dermatological, cosmetic or food domains, of alkylmonoglucosides as transcutaneous or transmucous membrane molecular vectors having the general formula: 
in which R1 is a C2 to C18 alkyl, linear or branched radical.
By xe2x80x9cmolecular vectorxe2x80x9d a compound is meant, which after chemical reaction with an active compound gives a vectorized active compound which penetrates the skin or a mucous membrane more easily than the initial active compound.
The invention also concerns the use, in a pharmaceutical, dermatological, cosmetic or food composition, of vectorized active ingredients with the general formula: 
where R2 is a xe2x80x94COxe2x80x94R group where R is a hydrocarbonated, linear, branched, saturated or unsaturated ethylene radical; a group derived from retinol (vitamin A) or from one of its derivatives, notably retinoic acid, ascorbic acid (vitamin C) or one of its derivatives, of a tocopherol amongst which are vitamin E and the D vitamins; a group derived from polyphenols, for example a residue of polyhydroxylated derivatives of flavan; or a radical 
where X is an aliphatic chain which is functionalized or not.
In these vectorized active ingredients, the active molecule is linked by covalence to position 6 of the vector. The invention stems from the fact that we have reduced the toxicity of exfoliant agents used in cosmetics and/or dermatology by grafting onto xcex1-butylglucoside.
Cosmetic and/or dermatological compositions have, amongst others, a vocation of acting on the protection function of the skin which necessitates the direct influence of the condition of the corneal layer. It is known that if this corneal layer contains too many dead cells, it doesn""t protect any more. It must then be removed to allow another layer of cells to maintain an efficient barrier against external aggressions, and the cosmetic and dermatological active ingredients to penetrate it. Such is the known and allotted role of Alpha Hydroxy Acids or AHA.
The AHA are organic acids with an alcohol function on the neighbouring carbon of the one (in alpha position) carrying the carboxylic acid function. We group together more particularly glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid as well as certain analogues of AHA like salicylic acid and serine in this family of compounds.
These AHA have recognised and measurable efficacy but they also present some drawbacks. These AHA are often irritants and have a poor bioavailability: they sometimes penetrate too rapidly into the deep layers of the skin. In Parfums Cosmxc3xa9tiques Arxc3x4mes 122,66-72 (April, May 1995) improvements proposed by the suppliers of raw cosmetic materials are described to make these compounds less irritant and to slow down their penetration into the skin.
A proposed improvement attempt consists of encapsulating these AHA in capsules in order to slow down the diffusion of AHA. Unfortunately, it is difficult to know with exactitude the percentage of active ingredients encapsulated and even more difficult to evaluate the percentage of active ingredients liberated into the skin.
Another attempt consists of lipophilising these AHA by grafting a lipophile compound (fatty alcohol, alkyl chains) by esterification. However, the action of these compounds is reduced because of their lipophile nature. In fact, they diffuse only with great difficulty into the stratum corneum into which they are stopped by the presence of aqueous compartments in the intercorneocytory spaces.
We have expanded this reflection to saturated and unsaturated fatty acids. In fact, the corneal layer is made up of a compact mass of 20 layers of inactive cells, embedded in a system of double lamellar layers of lipids. This structure of the stratum corneum as well as the lipophile nature of the lipid barrier protects the skin against the drying out provoked by the imperceptible loss of transepidermal water. Cosmetic and/or dermatological compositions have, amongst others, a vocation of acting on the protection function of the skin and to improve the appearance. If the intercellular lipids of the corneal layer are altered, the skin no longer protects.
Unsaturated fatty acids, such as linoleic acid, are an important factor for the construction and repair of the lipid barrier. They function as precursor molecules for the synthesis of a signal substance which controls the proliferation and the activity of the cells.
In addition, unsaturated fatty acids also directly take part in the regulation of the cutaneous permeability. These are non occlusive lipophile substances capable of making a more or less continuous film at the cutaneous surface but above all likely to incorporate themselves in the intercellular cement thus playing an active role in the regulation of hydration. Their biological activity is regulated by the position of the double link closest to the terminal methyl group.
The clinically observed cases of cutaneous alteration like acne show that a sufficient supply of unsaturated fatty acids in the skin is necessary to maintain the functioning of the lipid barrier.
Unsaturated fatty acids thus have an essential role in the physiology of the skin. Their topical administration however poses problems, problems that we propose to resolve by vectoring them.
The action of these compounds are reduced as they only diffuse with difficulty into the stratum corneum: they are stopped by the presence of aqueous compartments contained in the intercorneocytary spaces. The grafting of these acids onto xcex1-butylglucoside increases the hydrophile nature and thus optimises the penetration of these active ingredients into the epidermis.
In addition, the penetration of these compositions into the epidermis poses a problem because of their lipophile nature. Their introduction into emulsions stabilised by a monolayer of tensioactives practically does not improve this state of fact given that these emulsions break as soon as they are applied onto the skin. An oily phase containing the unsaturated fatty acids thus rests on the surface of the skin. Thanks to the invention the increase of the hydrophilic nature by the hydroxyl functions free from the glucose part improves penetration and allows an optimised usage of unsaturated fatty acids in water in oil or oil in water emulsions.
By extension, this principle can be applied to numerous active lipophile compounds with a physiological action on the skin. As an example, we can cite the esterifiable derivatives of the lipophile vitamins A,D,E or F, essential oils, solar filters, anti-inflammatories as well as bio-stimulant agents of lipids and/or protein syntheses. The document FR-A-94 12005 exposes different solutions consisting of preparing oil emulsions in specific water.
Certain cosmetic, dermatological pharmaceutical active ingredients and/or food ingredients are unstable as they are sensitive to exterior factors like light or heat.
Moreover, different means have been used to stabilise these compounds. One of these means lies for example in blocking the sensitive site by esterification with phosphate, sulphate, and alkyl derivatives and to employ these derivatives instead of the non-modified compound. These derivatives have a less good activity and are sometimes more toxic than the active ingredient free by the presence of phosphated, sulphated or alkyl residues.
Another means consists of blocking the site with a glycosidic derivative. A precursor of active ingredients is thus obtained which after application on the skin is stopped by the cutaneous enzymes or is hydrolysed after oral administration. The active ingredient is then liberated. Thus, the patent EP-A-627441 describes the. preparation and the use of glucosylate of ascorbic acid topically, stopped by the enzymes of the skin which then liberate ascorbic acid. But the use of such derivatives also brings about the liberation of glucose at the surface of the skin which favours the development of pathogenic cutaneous flora.
The applicant has now found in an unexpected manner that certain alkylmonoglucosides and more particularly xcex1-butylglucoside, allowed all these improvements whilst avoiding the problems described in the prior art.
The present invention thus has as its principal object the preparation and use of alkylmonglucosides and more particularly xcex1-butylglucoside in a food, cosmetic, dermatological or pharmaceutical composition.
The alkylglucosides, more particularly xcex1-butylglucoside, as well as certain alkylglucoside esters, can be obtained by enzymatic route as is described in the patent application PCT/FR92/00782 belonging to the applicant.
The products stemming from this process are anomerically pure (xcex1) and are monoglucosides. Because of the quasi absence of anomer xcex2, the compounds thus obtained, have specific physico-chemical properties, such as the point of fusion and the solubility. The amphiphile nature makes the xcex1-butylglucoside miscible in all proportions with saturated and unsaturated acids in a melted medium and soluble in the aqueous mediums and polar organic synthesis solvents.
We can modify the active ingredients and/or ingredients by xcex1-butylglucoside to make them lipophile or hydrophilic. It thus becomes possible to modulate their physico-chemical behaviour as well as their penetration, which makes it possible to strongly reduce any risk of irritation.
The active ingredients possessing at least one acid or ester function are able to be grafted with the aid of a chemical or enzymatic catalyst, notably hydrolysed trialglycerols (E.C no. 3.1.1.3) which can act as carboxyesterase. We have used Novozym(copyright) or Lipozyme(copyright) as they are easily accessible commercial enzymes. The active ingredients to which the invention applies concerns those comprising for example:
At least one acid function and more particularly amino and xcex1-hydroxy acids such as glycolic acid, lactic acid, malic acid, tartaric acid, citric acid, gluconic acid, salicylic acid and serine.
An acid function and notably butyric acid, saturated and unsaturated fatty acids, and more particularly oleic acid, erucic acid, ricinoleic acid, linoleic acid, and alpha and gamma linoleic acid.
At least one ester function like methyl lactate, ethyl lactate, butyl lactate or any other esterified derivative of the acids mentioned above. It can be cetone esters and notably dihydroxyacetone ester. The ester used according to the invention includes one or several ester functions with linear or branched chain, saturated or unsaturated, with from 2 to 25 atoms of carbon, possibly comprising one or several substituents.
At least one carboxylic esterifiable function, and notably, vitamin derivatives such as retinol (vitamin A) and its derivatives (notably retinoic acid), ascorbic acid (vitamin C) and its derivatives, tocopherols, amongst which are vitamin E and the D vitamins, as well as amino acids, peptides and their derivatives. It can also concern derivatives of polyphenols and more particularly polyhydroxylated derivatives of flavan and especially flavan-3-ol.
By vectorized active ingredients, we mean the coupling by a chemical covalent link of the active ingredient or ingredient to the position 6 of an alkylmonoglucoside and more particularly to xcex1-butylglucoside, of a formula 
in which R1 is C2-18 alkyl, linear or branched radical, preferably a butyl radical.
The vectorized active ingredients can be used according to the invention in a quantity from 0.1 to 50% in weight, and preferably from 0.5 to 50% in weight when it concerns vectorized cetone ester and notably vectorized dihydroxyacetone ester and from 0.1 to 10% in weight where other vectorized active ingredients are concerned.